\centering
\begin{tabular}{lll}
  \toprule
  & \multicolumn{2}{c}{常用工具} \\
  \cmidrule{2-3}
  \input{texlet/tab-base-header}
  \midrule
  \input{texlet/tab-base-win}
  \input{texlet/tab-base-unix}
  \input{texlet/tab-base-mac}
  \input{texlet/tab-base-cross}
  \bottomrule
\end{tabular}
